The Harvard experimentalists saw that loosely packed cells in the middle of a growing colony tend to swirl in a disorganized manner, and the simulations confirmed this. These swirls are analogous to what is seen in other examples of flocking. But when a wound is introduced, the swirls disappear and cells begin to match direction and velocity and pull toward a common goal. The ones on the edge immediately know which way to go, and everyone else learns from their example. Surprisingly, Levine said, "stickier" cells tend to push forward unevenly, with finger-like protrusions at the leading edge, much like what experimentalists often see.
The simulation model has a long way to go, Levine said. "It's rough around the edges. Biologists who read this will immediately say, 'You've left out all sorts of interesting things we know are happening.'
"Yes, there will be experiments for which this approach will not be sufficient," he said. "It will teach us that in those cases, biology has to exert a more specific role in creating the structures and the motion."
Levine hopes to match the models to current work by experimentalists on motility in cells related to the metastatic spread of breast cancer. "We're a long way from saying anything about this problem," he said. "But that's my overall agenda -- to push my research to where it can make contact with the cancer community."
|Contact: David Ruth|